<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        let  i= +prompt('第一个数'),e=+prompt('第二个数'),f=prompt('输入运算符')
        switch(f){
            case'+':
             alert(i+e)
            break;
             case'-':
             alert(i-e)
             break;
            case'*':
             alert(i*e)
             break;
             case'/':
             alert(i/e)
             break;
             case'%':
             alert(i%e)
             break;
             default:
                 alert(不符合)
                 break;
        }
    </script>
</body>
</html>